Method of frosting glass articles



Oct. 6, 1942. M. PIPKIN METHOD OF FROSTING GLASS ARTICLES Filed April 7,1959 'Invenbof: v Marvin PipKin, y W

His

c?) Attorney.

Patented Oct- 6, 1942 METHOD OF FROSTING GLASS ARTICLES Marvin Pipkin,Cleveland Heights, Ohio, assignor to General Electric Company,

New York a corporation of Application April 7, 1939, Serial No. 266,601

My invention relates in general to atmetnod of frosting the surface ofglass articles, and more particularly to a method of frosting theinterior surface of electric lamp bulbs. Still more particularly, myinvention relates to a glass article having a frosted surface ofdistinctive structure.

One object of my invention is to provide an electric incandescent lampbulb with a relatively rough inside frosted surface which will diffusethe light rays from the filament to such an extent as to eliminateimages of the so prevent the occurrence of a bright spot of light withinthe bulb.

Another object of my invention is to provide a novel method for theproduction of 'a relatively heavy frost of distinctive structure on thesurface of glass articles.

Still another object of my invention is to provide a reflecting electricincandescent lamp of distinctive appearance and structure in which allsharp images of the lighted filament, as well as the intense mirroreffect of the reflecting coating, are eliminated.

Further objects and advantages of my invention will appear from thefollowing detailed description of species thereof and from theaccompanying drawing, in which:

Fig. 1 is a longitudinal sectional view of a lamp bulb illustrating astep in the production of the inner frosted surface according to myinvention: Fig. 2 is an elevation partly in section of the completedlamp bulb comprising my invention; Fig. 3 is an elevation of amodification of the invention in which a portion of the inner bulbsurface is covered with a reflecting coating; and Fig. 4 is afragmentary sectional view, on an enlarged scale, of the bowl portion ofthe bulb shown in Fig. 2, illustrating the structure of the heavyfrosted surface comprising my invention.

Referring to the drawing, a glass bulb such as is employed for electricincandescent lamps is shown at i8. According to the inv ration, theentire inner surface of the bulb, or only a portion thereof, is providedwith a rough or heavy frost of distinctive structure, as indicated at Hin Fig. 2. This heavy inner frost is formed by the method comprising myinvention, as described hereinafter.

-As showninE-igLthebulb llisfirstfilled with a quantity material such aswhich varies. and the bulb position. but preferably mercially known asNo.

lead bird shot t2, the size of placed in an upri t finer than that com-A sufllcient should not be shot.

filament and of small globular acid-resistin The shot may be of anydesired size,

- only the bowl portion an etching solution in with sufficient lead shotthe rays of light emanatin from a amount of shot is inserted to coverthe ixmer surface area to be provided with the heavy frost.

according to the invention. In the particular form illustrated in thedrawing, the bulb is filled to cover approximately the lower half orbowl only of the bulbous portion of the bulb. An etching solution thatwill etch the glass, such acid, is then poured into the bulb so as tojust cover the lead shot II. This treating solution is allowed to act onthe glass of the bulb for a period of from five to ten minutes withoutany movement or disturbance of the bulb or its contents, so that thelead shot I! is maintained in fixed relation to the inner bulb surfacethroughout the etching operation. The etching solution and the lead shotI: are then poured out simultaneously and the bulb washed out.

As shown in Figs; 2 and i, the above-described etching process producesa frosted surface of distinctive structure consisting of a myriad ofround peaks or protuberances I3 all separated by relatively large,rounded and interconnected valleys or depressions. With such an etchedsurface,

filament 'located within the bulbous portion of the bulb arediiiusedtosuchanextentastoeliminate any sharp filament images or brightspots within the bulb.

In the bulb illustrated in Figs. 1 and 2, in which is provided with thefrosted inner surface according to the invention, it is desirable toprovide the remainder of the. inner bulb surface with a relatively lightfrost or etch ll (Fig. 2), such as is employed at present onconventional electric incandescent lamps. This secondary frostingoperation is preferably carried out by first covering the heavy frostedsurface li with a suitable acid-resistin medium, such as parafline wax,and then treating the re-.- maining exposed inner surface of the bulbwith the manner customary for the production of conventional insidefrosted lamp bulbs. The wait covering on the heavy frostedsurface iiisthenremovedinanysuitable way, such as by dissolving- In themodification shown in Fig-3, the lamp bulb there shown is the same asthat shown in Fig. 2 with the exception that the bowl portion, i. e..the portion provided with the heavy inside frosted surface II, iscovered with an inner reflecting coating l5 of aluminum or silver, orany other suitable reflecting material. The result is a reflectingsurface having a myriad of relatively small depressions or dimples l6therein readily as 30 per cent hydrofluoric 1 visible to the eye andpresenting a pebbled appearance. Such a reflecting surface givesdiffusion to the light rays emanating from the filament, thuseliminating all sharp images of the filament. In addition, such areflecting surface l5 eliminates the intense mirror eil'ect normallycharacteristic of a bulb provided'with a reflecting coating on a plainglass surface.

While I have described my invention in connection with the production ofinteriorly frosted electric incandescent lamp bulbs, it is obvious thatit may be applied equally as well to the outer surface of such bulbs orto the frosting of flat glass surfaces.

What I claim as new and desire tosecure by 15 Letters Patent if theUnited States is:

A method for the production of inside frosted bulbs which" comprisespartly filling said bull: with a quantity of loose but closely packedrelatively small globules of a substantially acidresisting material.treating the inner bulb surface covered by said acid-resting materialwith an etching solution while maintaining said acidresisting materialin fixed relation to said surface, removing said solution and saidacid-resisting material from said bulb, washing the treated innersurface of said bulb and entirely covering the said treated surface witha layer of acidresisting material. treating the remainder of said innerbulb surface with an etching solution, and

removing said layer of acid-resisting materiaL.

- MARVIN PIPKIN.

